To determine if CPAP treatment will reduce the rate of cardiovascular events in patients with acute coronary syndrome and co- occurring sleep apnea. [ Time Frame: Twelve month after the inclusion of the last patient ] [ Designated as safety issue: No ]

Severity and phenotype of patients with OSA and clinical outcomes of ACS. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

CPAP compliance and CV events incidence. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

Biological risk markers related to mechanisms involved in cardiovascular complications in these patients. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

Cost-effectiveness analysis (Qualys) of the diagnosis and CPAP treatment of patients with ACS who have obstructive sleep apnea. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

Original Secondary Outcome Measures ICMJE (submitted: April 13, 2011)

Determine the prevalence of OSA in patients who have suffered an episode of ACS. [ Time Frame: 24 month (inclusion period) ] [ Designated as safety issue: No ]

Determined at the inclusion of the patient

To evaluate the effect of CPAP on a composite of CV death, myocardial infarction (MI) and ischaemic stroke. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To evaluate the effect of CPAP on the components of primary composite endpoints [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To evaluate the effect of CPAP on the number of re-vascularization procedures [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To evaluate the effect of CPAP on all-cause death [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To evaluate the effect of CPAP on the new onset, ECG-confirmed atrial fibrillation or other arrhythmias [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To evaluate the effect of CPAP on newly diagnosed diabetes mellitus, according to standard definitions. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To evaluate the effect of CPAP on OSA symptoms (Epworth Sleepiness Scale (ESS)) and quality of life ((Test EuroQol (EQ-5D) [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To establish the relationship between the severity and phenotype of patients with OSA and clinical outcomes of ACS. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To establish the relationship between CPAP compliance and CV events incidence [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To identify biological risk markers that allow us to establish the most important mechanisms involved in cardiovascular complications in these patients. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

To conduct a cost-effectiveness analysis of the diagnosis and CPAP treatment of patients with ACS who have obstructive sleep apnea. [ Time Frame: 12 month after the inclusion of the last patient ] [ Designated as safety issue: No ]

OSA may be a modifiable risk factor for cardiovascular disease due to its association with hypertension, stroke, heart attack and sudden death. The standard therapy for symptomatic OSA is continuous positive airway pressure (CPAP). CPAP has been shown to effectively reduce snoring, obstructive episodes and daytime sleepiness and to modestly reduce blood pressure and other risk factors for cardiovascular disease. The overall aim of ISAACC is to determine if CPAP can reduce the risk of heart attack, stroke or heart failure for people with OSA admitted in a hospital for an acute coronary syndrome.

Overall objective:

To assess the impact of obstructive sleep apnea (OSA) and its treatment on the clinical evolution of patients with acute coronary syndrome (ACS).

Duration of the study: 3 years. Methodology: During a hospital stay we will assess the degree of daytime sleepiness (Epworth Scale) in patients treated at the Coronary Care Unit with a diagnosis of ACS. The results of this evaluation will define the inclusion of the patient in the study.

Patients with and ESS score ≤ 10 will be included in the study and will undergo a cardio-respiratory polygraphy. Patients with an AHI ≥ 15 h-1 will be randomized to CPAP treatment or conservative. Patients with and AHÍ < 15 h-1 will be followed as standard management according to cardiovascular protocols and will be evaluated as a reference group. Therefore, the study will have three groups, with a total of 1,864 patients, as follows: patients with an AHI ≥ 15 h-1 will be randomized to CPAP treatment (Group 1) (n=632) or conservative treatment (Group 2) (n=632). Patients with an AHI < 15 h-1 that will be followed as a reference group (Group 3) (n=600).

Patients with an ESS score higher than 10 will be excluded of the study and referred to the sleep unit of each participating center for evaluation.

Patients included in the study will be monitored and followed for a minimum of one year and a maximum of three years. Patients will be examined at the time of inclusion (T0), after one month (T1), three months (T2), six months (T3), 12 months (T4) and every six months thereafter, if applicable, during the follow-up period. Evaluations will include; i)new episodes of ACS, stroke, TIA, heart failure, hospitalization for cardiovascular causes and cardiovascular mortality, ii) biological risk markers involved in cardiovascular complications, iii) an evaluation of the cost-effectiveness of diagnosis and CPAP treatment in patients with ACS who have obstructive sleep apnea.

Patients with conservative treatment: (Group 2). This group will also be instructed in hygienic-dietary measures, standard care of cardiovascular risk factors and sleep hygiene counselling.

Device: continuous positive airway pressure

Patients with CPAP treatment (Group 1): CPAP pressure titration will be performed by automated equipment before discharge. It will follow the methodology described by our group (Mass et al. Alternative Methods of titrating continuous positive airway pressure: a large multicentre study. American Journal of Respiratory and Critical Care Medicine (2004) vol. 170 (11) pp. 1218-1224). This group will also be instructed in hygienic-dietary measures recommended for all patients, standard care of cardiovascular risk factors and sleep hygiene counselling.

A medical history that may interfere with the study objectives or, in the opinion of the investigator, compromise the conclusions.

Any medical factor, social or geographical, that may jeopardize patient compliance.(e.g., alcohol consumption (more 80 gr/day in men and more than 60 gr / day in women), no fixed address, disorientation, or a history of non-compliance).

Any process, cardiovascular or otherwise, that limits life expectancy to less than one year.

Patients in cardiogenic shock who have poor expectations for short-term outcomes.